In recent years, the implementation of an ultrahigh-speed and large-capacity wireless communication is intensely demanded and the development of a broadband circuit component covering a millimeter-wave band of 59 to 66 GHz not requiring license stipulated by the Radio Law has been important. By this, an ultrahigh-speed radio LAN, a home link, a broadband radio access system, a vehicle-to-vehicle communication system and the like can be realized at a transmission rate exceeding 1 Gbps for example.
And as a transmission line for such a millimeter wave of 60 GHz band, there is known an NRD guide composed by inserting a dielectric strip being square in section into a cut-off parallel plate waveguide (see patent literature 1, for example).
An NRD guide is composed by disposing a dielectric strip being square in section between a pair of conductor plates of about 4.0 mm in thickness being arranged above and below in parallel with each other at a specified interval. A good electrically conductive and non-magnetic material such as aluminum, copper, brass or the like is used as the conductor plate. And a dielectric substance being low in loss in a high-frequency band like a millimeter-wave band, said dielectric substance being 3.0 or less in dielectric constant ∈r, such as Teflon (trademark) of ∈r=2.04, polyethylene of ∈r=2.1, polystyrene of ∈r=2.56 or the like for example is used as a dielectric strip.
FIG. 20 is a configuration diagram in case of applying such an NRD guide to an NRD guide receiver in an NRD guide multi-channel television signal transmission system. A 60-GHz band millimeter wave received by a receiving antenna 102 of an NRD guide receiver 101 is divided into two through a 3 dB NRD guide coupler 107 composed of a pair of curved dielectric strips 105, 106 disposed between a pair of conductor plates 103, 104.
The radius of curvature r and the angle θ of the curved portion of the dielectric strip 105 are set as r=10 mm and θ=110 degrees. And the radius of curvature r of the curved portion of the dielectric strip 106 is set as r=43 mm. The dielectric strip 106 may be formed into the shape of a straight line. A 60-GHz band millimeter wave is divided into two by the NRD guide coupler 107 and thereafter introduced into balance mixers 108, 109.
The balance mixers 108, 109 have a structure performing mixing by means of two Schottky barrier diodes 110, 111 and being made high in sensitivity. And Teflon (trademark) chips 112, 113 attached to the front faces of mounts of the Schottky barrier diodes 110, 111 protect the Schottky barrier diodes 110, 111 from being broken. In similar manner, high-permittivity films (not illustrated) attached to the back faces of the mounts of the Schottky barrier diodes 110, 111 match the Schottky barrier diodes 110, 111 being low in resistance and the dielectric strips 105, 106 being high in impedance with each other. Further, Teflon (trademark) chips 114, 115 mounted on the back of the high-permittivity films make higher the matching with the NRD guide coupler 107.
An oscillation signal from a Gunn diode oscillator 116 having a Gunn diode mounted on a metal piece being H-shaped in section is led to the dielectric strip 106 through a metal strip resonator 117. And a mode suppressor 118 is inserted to an end portion of the dielectric strip 106 in order to suppress an undesired mode generated at the joint portion with the metal strip resonator 117. Further, a ceramic resonator 119 for stabilizing the frequency is disposed so as to side-couple near the dielectric strip 106. The ceramic resonator 119 is composed of a high-Q ceramic disk held by Teflon (trademark) disks from above and below between them, and the ceramic disk is placed in the middle of the conductor disks 103, 104 so as to remove emission. The ceramic disk is 0.47 mm in thickness and has a resonance frequency of 59 GHz.
A 59-GHz oscillation signal from the Gunn diode oscillator 116 is applied by the dielectric strip 106 through the NRD guide coupler 107 to the balance mixers 108, 109, is down-converted there and is outputted to a terminal 120 as an IF signal.
On the other hand, as an apparatus for performing downloading, recording, reproducing or the like of video data, up to now there have been a portable DVD player for reproducing video data recorded in a DVD, a solid player which has a storage portion, transfers and stores video data into this storage portion and reproduces this stored video data, a portable liquid crystal television for receiving and reproducing video data broadcasted, a notebook-sized personal computer capable of storing and reproducing video data in a large-capacity memory such as a hard disk or the like, and the like.
Patent literature 1: Japanese Patent Laid-Open Publication No. 2000-59,114
Patent literature 2: Japanese Patent Laid-Open Publication No.2002-092,571